Creating a PC board (PCB) layout for a circuit in which the components of the circuit are placed in the determined PCB landing areas

ABSTRACT

A method and apparatus for PCB layout of a circuit simulated over a network is provided. Techniques are provided for designing a circuit that satisfies user-specified functional requirements received over a network. Based on the specified requirements, components and a topology for constructing the circuit are automatically determined. The components determined during this operation have operational values such that, when the components are arranged according to the topology to form the circuit, the circuit satisfies the user-specified functional requirements. The components are placed on a PC board having landing areas designed to accommodate all of the anticipated component sizes for the type of circuit being designed. The PC board may be cropped to the desired size. The PCB may be cropped automatically or manually by the user. The component and topology information may be used to generate a schematic diagram that is delivered in a web page to the user over the network. The user may thermally and electrically simulate the designed circuit. Many characteristics of the PC board may be adjusted to produce an accurate circuit.

FIELD OF THE INVENTION

The present invention relates to layout for an electrical circuit, andmore particularly to creation of a PC board layout according to specificdesign criteria.

BACKGROUND OF THE INVENTION

Many times when a user requires a circuit, the user frequently knowslittle more than the requirements that the circuit must satisfy. Toobtain the desired circuit, the user may provide a list of therequirements to a business that is knowledgeable about those types ofcircuits, how to design them, and where to obtain the components tofabricate them. The business may then construct and supply the user withthe circuit. The business may have a significant price mark up for theseservices.

To avoid having to pay the marked up prices, the user may attempt tobecome educated on circuit design, obtain parts catalogs from circuitcomponent suppliers, and fabricate the circuit. However, the effort andcost required to gain the requisite education and knowledge may not beworthwhile. To reduce the effort required to perform some of thesetasks, the user may obtain and install specialized client-side tools,such as the Switchers Made Simple software product available fromNational Semiconductor Corporation. While such tools may assist in thecircuit design and component selection tasks, the user must still gothrough the manual process of placing orders for the components.Further, given the rapidity with which circuit component manufacturerschange their product lines, the component information used by thespecialized client-side software will quickly become outdated unlessfrequently updated. The inconvenience of having to obtain, install, andkeep such specialized software updated does not make this the solutionideal.

Even after a working circuit is designed, the circuit components need tobe arranged on a PC board (PCB). The placement of components on the PCBmay affect the thermal and electrical characteristics of the circuit.Thermal characteristics affect the operating characteristics of thecircuit and the thermal behavior of a circuit may be affected by thelayout of the components on a board. For example, if components arelocated close together on a board, they may overheat, and if a componentin a circuit becomes too hot its lifespan may become limited. A usermight also have to become familiar with the operating characteristics ofeach component, as well as the interaction between the components. Thisoften is not practicable. PCB design and layout is yet one moreinconvenience confronting users designing their own electronic circuits.

SUMMARY OF THE INVENTION

The present invention is directed at creating a PC board layout for acircuit based on parameters of the circuit.

According to one aspect of the invention, the components of the circuitare determined. The components may be determined from a simulation ofthe circuit, including a thermal simulation and an electricalsimulation.

According to another aspect of the invention, appropriate landing areason the PCB are selected to place the components. The landing areas mayinclude an inductor area, an output capacitor area, a diode area, asmall signal component area, an IC area, and an input capacitor area.

According to still yet another aspect of the invention, the PCB may becropped to a size. The size may be determined automatically, or may bemanually set by the user. The cropping removes unneeded area from thePCB.

According to another aspect, a network tool allows a user to input theirdesign criteria, select circuit parts based on their design, create anelectronic circuit design based around the selected parts, conductthermal simulations of the design, and order components, a kit, or acompleted board for the design.

According to a further aspect of the invention, components and atopology for constructing the circuit are automatically determined. Thecomponents determined during this operation have operational values suchthat, when the components are arranged according to the topology to formthe circuit, the circuit satisfies the user-specified functionalrequirements. One or more web pages that identify the components arethen delivered over the network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 illustrate an exemplary environment for practicing theinvention;

FIG. 4 is a block diagram that gives an overview of functional modulesused to implement an embodiment of the invention;

FIG. 5 shows an overview flow diagram illustrating general steps of thethermal simulation process;

FIG. 6 illustrates an exemplary web page for starting the designprocess;

FIG. 7 shows an exemplary requirements web page for receiving therequirement information from a user for a power supply circuit;

FIG. 8(A and B) is an example of a suggested component web pagegenerated in response to the requirements specified according to FIG. 7;

FIG. 9 shows an exemplary web page illustrating a product folder webpage;

FIG. 10(A and B) illustrates an exemplary bill of materials web page;

FIG. 11(A and B) illustrates an exemplary web page showing alternatecomponents for a component;

FIGS. 12A and 12B show exemplary web pages illustrating operating valuesof a circuit;

FIG. 13 shows an exemplary schematic diagram;

FIG. 14 illustrates a control panel window for helping to control theelectrical simulation of the circuit shown in FIG. 13;

FIG. 15 illustrates an exemplary web page listing instructions toconduct a thermal simulation;

FIGS. 16A and 16B show an exemplary web screen illustrating setup ofthermal simulation of the circuit designed according to the user'srequirements;

FIGS. 17-19 illustrate exemplary simulation status screens;

FIGS. 20A and 20B show an exemplary result of a thermal simulation;

FIGS. 21A and 21B show an exemplary web page illustrating the results ofa simulation with the changed parameters;

FIGS. 22A and 22B show an exemplary BUILD IT web page;

FIGS. 23A-23F illustrate an exemplary assembly diagram;

FIG. 24 illustrates an exemplary documentation page;

FIGS. 25A-25E illustrate an exemplary design document;

FIG. 26 shows an exemplary MY designs page;

FIG. 27 shows the process of a PC board layout;

FIG. 28 illustrates the allocation areas of a PCB;

FIG. 29 illustrates cropping a PCB; and

FIGS 30A and 30B illustrate exemplary PC board (PCB) layouts, inaccordance with aspects of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description of exemplary embodiments of theinvention, reference is made to the accompanied drawings, which form apart hereof, and which is shown by way of illustration, specificexemplary embodiments of which the invention may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the present invention. Thefollowing detailed description is, therefore, not to be taken in alimiting sense, and the scope of the present invention is defined onlyby the appended claims.

PC Board Layout

FIG. 5 shows an overview flow diagram illustrating general steps of theprocess, according to aspects of the invention. After a start block, thelogical flow moves to a block 510 where the user chooses a part orinputs their system specifications to find those parts that fit (SeeFIG. 7 and related discussion). Moving to a block 520, a design iscreated that includes the components and calculated operating values forthe part (See FIG. 8(A and B) and related discussion). Stepping to ablock 530, the PCB layout of the components is performed. Generally, thecomponents are placed in predetermined landing areas on the PCB based ontheir use (See figures and related discussion below). Transitioning to ablock 540, the design may be analyzed. The design may be analyzed usingan online thermal or electrical simulator to visualize and obtain thethermal and electrical behavior of the design (See figures and relateddiscussion below). Moving to block 550, the circuit may be ordered. Apart, a kit of parts, or an evaluation board may be ordered from asupplier.

FIG. 27 shows the process of a PC board layout in accordance withaspects of the invention. After a start block, the logic moves to block2710 at which point the process determines what components are to beplaced on the PCB. Stepping to block 2720, the location to place thecomponents on the PCB are determined. The PCB is designed such that thecomponents for the circuit design may be located at predeterminedpositions. Transitioning to block 2730, the components are placed on thePCB. Moving to block 2740, the PCB may be cropped to remove any unusedPCB space (See FIG. 29 and related discussion).

FIG. 28 illustrates the allocation areas of a PCB, according to anembodiment of the invention. As shown, PCB 2800 includes circuit board2805, inductor area 2810, output capacitor area 2815, diode area 2820,IC area 2825, small signal component area 2830, input capacitor area2835 and connection lines 2840.

Inductor area 2810 is sized such that there is sufficient area to placethe inductors used in the design of the circuit. Output capacitor areais sized such that there is sufficient area to place the outputcapacitors used in the design. Diode area 2820 is sized such that thereis sufficient area to place the diodes used in the design. IC area 2825is sized such that there is sufficient space to place the IC used in thedesign. According to one embodiment of the invention, the IC used in thedesign is placed in a fixed location on circuit board 2805. Small signalcomponent area 2830 is sized such that there is sufficient space toplace the small signal components used in the design. According to oneembodiment of the invention, the small signal components utilized areplaced at fixed locations within small signal component area 2830. Inputcapacitor area 2835 is sized such that there is sufficient area to placethe input capacitors used in the design.

While the component area sizes are shown for power circuits, othercircuits may utilize the predetermined landing area approach.Accordingly, the areas shown in the figures may be designed toaccommodate the different design requirements.

FIG. 29 illustrates cropping a PCB in accordance with aspects of theinvention. As shown in the figure, cropped PCB 2900 includes circuitboard 2905, width controls 2910, height controls 2915, deleted widtharea 2920, and deleted height area 2925. The PC board layout is createdfor the user by printed circuit board layout module 418 (See FIG. 4 andrelated discussion). The appropriate layout is selected based oncritical parameters. For example, the parameters may include: thetopology of the circuit, the IC selected, the size of the selectedcomponents, whether the design requires a large amount of copper todissipate heat or a heat sink to dissipate heat, and the like.

The user may define the size of the boards by adjusting controls 2910,and 2915. By adjusting the controls, the user may remove the unnecessarycopper areas from the PC board. According to one embodiment of theinvention, the user may perform a thermal simulation of the board basedon the newly defined board size.

Width controls 2910 may be positioned to delete a portion of the widthof the board. The width may be adjusted manually by the user orautomatically. The user may adjust the width of the PCB by selectingwidth controls 2910 and sliding the controls to a desired width.According to the present example, width controls 2910 have been moved todelete width area 2920.

Similarly, height controls 2915 may be positioned to delete a portion ofthe height of the board. As shown, height controls 2915 have beenadjusted to delete height area 2925. A user may adjust the height of thePCB by selecting height controls 2915 and positioning the controls toremove the desired portion of the board.

After the cropping width and height of the board are determined the PCBis cropped according to the specifications. The width and height of thePCB may be cropped automatically based on the components used in thecircuit. PCB layout module 418 (See FIG. 4 and related discussion) mayautomatically determine where the components are placed on the PCB anddelete the portions of the board not used by the components.

FIGS. 30A and 30B illustrate exemplary PC board (PCB) layouts. The PCBlayout of the design is created such that the landing pads for thecomponents used are large enough to accommodate many different sizes andvarieties of surface mount components, which may vary from design todesign. Some of the parts, such as the IC may be through hole mount ifthese parts conform to a specific pin pattern specified for that board.This way, one PCB layout may be used for many different designs. Forexample, a PCB layout may be set up for the pinout of a specificNational Semiconductor device such as the LM2678. The copper tracesleading into this part are small since this part does not change in sizefrom design to design for that layout. However, to accommodate theessentially infinite number of combinations of accompanying components,which vary in size and shape, the landing pads for these components aremade large enough and spaced closely enough to accommodate the differentsizes of components foreseen for that PCB layout.

According to one embodiment of the invention, a system is provided bywhich users, with no or little special client-side software, and littleor no knowledge of available circuit components, can easily andefficiently create, test, and order circuits and components that satisfytheir functional requirements. According to one embodiment of theinvention, the user is presented with a series of web pages to achievethis result.

FIG. 4 shows a block diagram that gives an overview of functionalmodules 234 used to implement the techniques described hereafter.Functional modules 234 (FIG. 2) include numerous functional modules.Referring to FIG. 4, in the illustrated embodiment, the modules 400include requirements form module 410, component determination module412, circuit design module 414, schematic design generation module 416,PC board layout module 418, thermal simulation module 422, and componentacquisition module 424. The functions of each of these modules shall bedescribed in greater detail hereafter.

FIG. 6 illustrates an exemplary web page for starting the process fordesigning a circuit. The web page illustrated contains text 610 thatexplains the four general steps of the process to the user, and containslinks to web pages for “Choose a Part” 620, “Create a Design” 630,“Analyze a Design” 640, and “Build It” 650 that contain more informationrelating to the four general steps. The page contains links to theuser's recent designs 660, a “MyDesigns” link 670 to all of the user'sdesigns, as well as a link to electrical simulations 680, thermalsimulations 690, and the user's “BuildIt” orders 695.

When the user desires to start the process the user may select the STARTHERE link 605. It should be noted that many of the links and buttons “toweb pages” are actually links that result in the execution of softwaremodules which produce, as output, the web pages that are delivered tothe user. Selecting START HERE link 605 directs the user to the web pageas illustrated in FIG. 7.

Suggesting Components Based On User-Specified Requirements

For the purpose of explanation only, it shall be assumed that a userdesires to create a power supply. Accordingly, the user selects STARTHERE LINK 605 shown in FIG. 6. While the techniques described hereinshall be described in the context of designing, simulating, and orderingparts for a power supply circuit, the techniques are not limited to anyparticular type of circuit.

According to one embodiment, a web server, such as web server 200 (FIG.2) responds to selection of START HERE link 605 by invoking therequirements form module 410. The requirements form module 410 providesone or more “requirements” web pages to client computer 300. Therequirements web pages allow the user of the client to specifyrequirements for a circuit.

FIG. 7 shows an exemplary requirements web page for receiving therequirement information from a user for a power supply circuit. Theillustrated requirements page includes user interface controls forspecifying minimum and maximum input voltages (controls 702), and anoutput voltage and current (controls 704). The requirements web pagefurther includes controls 706 for additional requirements, such aswhether the circuit requires an ON/OFF pin, an Error Flag, Sync Pin, ormultiple output voltages and currents. Other requirements that may applyto a power circuit, for example, may include requirements associatedwith efficiency, frequency, and the like. It should be noted that thespecific user interface controls presented by the requirements web pageswill vary from implementation to implementation based on a variety offactors, including the type of circuit for which the requirements arebeing specified.

The requirements information entered by the user into the requirementsweb page may be transmitted back to the web server. The operation ofsending the requirements information to the server may be initiated, forexample, by the user selecting a particular control, such as button 708,on the requirements web page.

Based on the requirements information, a component determination module412 determines the components that could be used to build a circuit thatwould satisfy the specified requirements, and generates one or more“suggested component” web pages. The process of determining thecomponents that could satisfy the specified requirements may beimplemented, for example, by applying filters to component data storedin a database. The filters may, for example, compare the valuesspecified in the “output voltage” and “output current” fields of therequirements web page against values in corresponding columns of a“component” table in a database.

The process may also involve using values from the requirementsinformation as input into formulas, where the output of the formulas isused to determine which components could satisfy the specifiedrequirements. For example, assume that the user desires a boostregulator circuit. Integrated circuits used in boost regulators have aswitch current rating. The switch current rating of each integratedcircuit that can be used in a boost regulator may be stored in therecord for that integrated circuit in a database. To determine whichintegrated circuit may be used, the input voltage, output voltage andoutput current specified in the requirements information are used tocalculate a required switch current rating, and the required switchcurrent rating is compared against the switch current ratings in thedatabase to select those integrated circuits within the database thatcan satisfy the specified requirements.

FIG. 8 is an example of a suggested component web page generated inresponse to the requirements specified according to FIG. 7. In thepresent example, the suggested components fall into two categories:switching regulators for use in a Buck Topology, and switchingregulators for use in a Flyback Topology. An understanding of thedistinction between these categories of switching regulators is notimportant for the purpose of understanding the techniques describedherein. However, such distinctions may be relevant to the user designingthe power circuit. Therefore, component determination module 412generates the suggested component web page in a manner that groups thesuggested components into those and any other applicable categories.

Component determination module 412 further includes in the suggestedcomponent web page other information relevant to the user's selection ofa component. In the illustrated embodiment, the other informationincludes the maximum current, the typical efficiency, whether thecomponent has an ON/OFF pin or an Error pin, a field for “otherfeatures”, the frequency of the component and an estimated price of thecomponent. Other information may be included in the display. Forexample, the number of components in stock and the physical size of thecomponents may be displayed. Additionally, a diagram of the componentmay be shown.

In the illustrated implementation, the names of the suggested componentsare presented in the form of links. Selection of the link associatedwith a component results in the delivery of a “product folder”.According to one embodiment of the invention, the product folder is aweb page that presents detailed information about a component. Forexample, selecting link 802 associated with the LM2679-ADJ componentproduces the product folder web page as shown in FIG. 9. The informationand controls contained on the product folder web page of a componentshall be described in greater detail hereafter.

The information contained in the suggested component web pages, and theproduct folders of the components listed in the suggested component webpages, satisfies only part of the users needs. In particular, the useris interested in creating an entire circuit that satisfies the specifiedrequirements, and not merely in identifying a component that could beused in such a circuit. Therefore, according to one embodiment of theinvention, the user is presented with a control for automaticallygenerating the design of such a circuit using a component selected fromthe suggested component web pages.

A thermally enabled indicator 806 is displayed for those parts that arethermally enabled. This allows the user to quickly identify parts thatmay be simulated using the thermal simulation tool. A build it indicator808 is displayed for those parts that may be purchased in a custom kit.In addition to the information currently displayed, other informationmay be displayed. For example, the total bill of materials (BOM) pricemay be displayed. This may be useful information to help the user decidewhich part to select. According to one embodiment of the invention, whenthe part is not thermally enabled, the user may supply the thermalrequirements data for the component so that the component may bemodeled.

AUTOMATIC CIRCUIT DESIGN

Referring again to FIG. 8, the listing for each component includes afield that contains a CREATE DESIGN button, such as CREATE DESIGN BUTTON804, which, when selected, causes the automatic generation of a circuitdesign that uses the selected component, and satisfies the specifiedrequirements that were initially entered by the user. For example,assume that the user determines, based on the information contained onthe suggested components web page and, optionally, the more detailedinformation on product folder web pages, that the LM2679-ADJ componentis the best of the suggested components for the user's purpose. The usermay then select CREATE DESIGN BUTTON 804 associated with that componentto cause generation of a power circuit that uses the LM2679-ADJcomponent, and satisfies the requirements specified on the requirementsweb page shown on FIG. 7.

According to one embodiment, selection of a create design button causesa message that indicates the requirement information and identifies theselected component to be sent to a circuit design module 414. Inresponse, circuit design module 414 designs a circuit that uses theselected component and satisfies the specified requirements.Specifically, circuit design module 414 determines components that areutilized in the circuit in addition to the selected component, and howthose components should be arranged to create the circuit (the circuit“topology”).

The circuit may contain many more components in addition to the selectedIC component. Rules and mathematical formulas are used to select theoptimal values for these additional components. These rules may be setup to optimize certain design criteria over another. For example, if theuser desires to have minimal output voltage ripple, a larger outputcapacitor value may be chosen, but this may degrade the circuit'sability to respond to a sudden change in input voltage (transientresponse). Thus, the user may be given a choice to emphasize one designcriteria over another.

One output of circuit design module 414 is a set of rules for theadditional components in the circuit. For example, for a certain designthe output capacitor must have a capacitance greater than or equal to100 μF and an equivalent series resistance of less than or equal to 100MΩ. These rules are used to select alternate components if desired.

Various techniques may be used by circuit design module 414 to determinethe topology of the circuit. For example, numerous topology “templates”may be stored on the server-side at a location accessible to circuitdesign module 414. Data may also be stored that associates general typesof circuits with one or more of the topology templates. In an embodimentof the invention that uses topology templates, circuit design module 414selects the topology template based on the type of circuit that is beingdesigned, and then uses the selected topology template, the selectedsuggested component, and the requirements information to determine theother components required for the circuit.

According to one embodiment, circuit design module 414 transmits back tothe user one or more components list web pages. The components list webpages identify the components that are included in the circuit designedby circuit design module 414 (referred to herein collectively as the“designed circuit components”). The designed circuit components thusinclude the selected component and the additional components determinedby circuit design module 414.

For the purpose of illustration, it shall be assumed that the userselects the create design button associated with the LM2679-ADJcomponent.

PRODUCT FOLDER WEB PAGES

FIG. 9 shows an exemplary web page illustrating a product folder webpage for the LM2679-ADJ component. In the illustrated embodiment, theproduct folder web page includes links 902 to related informationrelating to the component, including a General Description section, aFeatures section, an Applications section, a Datasheet section, aPackage Availability, Models, Samples & Pricing section, and a designtools section. A parametric table 904 showing the operating parametersof the component is also displayed.

The General Description section includes a general description of thecomponent. The Features section lists the features of the component. TheApplications section lists applications in which the component istypically used. The Datasheet section contains links to view online ordownload the data sheets for the component.

The Package Availability, Models, Samples & Pricing section listspackage types and other options available for the component, indicatesthe status, availability and price of the component for each option, andcontains controls which, when selected initiate an operation for placingan order or sample for each option for the component.

The Design Tools section includes a link (not shown) to view online ordownload information about software tools that may be used to assist indesigning circuits that use the component. Button 906 allows the user togo directly to WEBENCH if they got to the product folder first beforeentering WEBENCH.

Bill Of Materials

FIG. 10(A and B) illustrates an exemplary bill of materials web pagethat indicates the components used in the circuit design generated bycircuit design module 414. In addition to the selected LM2679-ADJcomponent, the bill of materials web page lists numerous other circuitcomponents from a variety of manufacturers. If the user desires tosubstitute any of the designed circuit components listed in the bill ofmaterials page for another component, the user may select the “selectalternate part” button associated with that component. In response toselection of the “select alternate part” button associated with acomponent, the user is presented with a list of alternate components.Such substitutions may be desirable, for example, if the user desirescomponents from a particular manufacturer. For example, suppose the userdesires to select an alternate component for component part D1, the userselects button 1002. The alternate components for component part D1 arethen displayed to the user (See FIG. 11(A and B) and relateddiscussion).

The bill of materials page provides user interface controls 1004allowing the user to edit the information stored about your simulation.All changes are stored automatically and associated with the user. Fileoperation copy allows the user to create an identical design, which canthen be altered for comparison. File operation rename allows the user tochange the label on the current design. File operation add allows theuser to add or edit notes stored with the design. File operation printallows the user to print a report of the design. XML file operationallows XML to be displayed. A web browser capable of displaying XML suchas Internet Explorer 5.0, is used for this feature. Share this designfile operation allows the design to be shared among colleagues. Forexample, the design engineer could share the design with other designersor with their supervisor.

A scale drawing of the top view of the components in the design isdisplayed if available. According to one embodiment, these drawingoutlines are stored in a database on a web server. The drawings are in acolor scheme similar to the actual colors of the components. Thisdisplay allows the user to see the size of the components, which isoften an important attribute to consider when creating a circuit design.If the component cannot be thermally simulated, the letter N isdisplayed instead of the scale drawing of the top view of the component.This allows the user to readily determine whether a component may bethermally simulated. In addition to the information shown, otherinformation may be included. For example, the number of components instock, the price, and the like may be shown.

Alternate Components

FIG. 11(A and B) illustrates an exemplary web page showing alternatecomponents for a component. The user may select from a list of suppliedalternate components or enter a custom component. Along with thealternate components, other information relating to the component isdisplayed to the user. For example, for the D1 component, the forwardvoltage drop, max rated current, max voltage rating, physical dimensionsof the component, price, quantity available, as well as if the componentis thermally modeled is displayed. The top view scaled drawing ofthermally simulated components is shown. There is also an indicator (theletter N) to show if the alternate component cannot be thermallysimulated. These features allow the user to view the size of alternatecomponents and choose parts that may be simulated using the thermalsimulator if so desired. On the alternate components screen, the user isallowed to manually enter the values for a component if desired.According to one embodiment of the invention, to allow a component to bethermally simulated, the user is given the option to enter simulationparameters including the x, y and z dimensions of the component, thepackage type of the component and a choice of a top view drawing to beused for the component.

The recommended limits for the important parameters for the componentare displayed (1108, 1110, and 1112). These are determined by componentdetermination module 412. This allows the user to better select analternate component or enter custom values. As will be appreciated,other information may also be displayed to the user. According to oneembodiment of the invention, when the user enters a custom component,the component cannot be thermally simulated. According to anotherembodiment of the invention, the user may enter the thermal parametersneeded to simulate the component. According to this particular example,the user has selected alternate component 5 to replace component D1shown in FIG. 10(A and B). Once the user has selected an alternatecomponent, the user selects Update BOM button 1102 to incorporate thecomponent into the design.

Referring again to FIG. 10(A and B), once the user has made any desiredcomponent substitutions, the user may select operating values control1006 to obtain operating value information for the circuit created bycircuit design module 414 using the parts listed in component listspage. FIGS. 12A and 12B illustrate exemplary web pages showing theoperating parameters for the circuit associated with the bill ofmaterials of FIG. 10(A and B) including the changed D1 component. Fromeither the components list web page or the operating values web page,the user may select “schematic” control 1008 to cause a schematicdiagram of the circuit to be generated.

In response to selection of schematic control 1008, one or more messagesidentifying the designed circuit components, as well as the topologydata for the generated circuit, are sent to a schematic diagramgeneration module 416. The schematic diagram generation module 416generates one or more web pages that include a schematic diagram of thecircuit, and delivers the schematic web pages to the user.

Operating Values

FIGS. 12A and 12B show exemplary web pages illustrating operating valuesof a circuit. The operating values provide the user with the results ofcalculations for the power supply design. These calculations may then beused in the selection of the design components, and are reported to givethe user an estimate of the circuit performance. According to oneembodiment of the invention, the operating values are updated when theuser changes the components. For example, when the user selects analternate component the operating values change. Referring to FIGS. 12Aand 12B, the operating values provide the Pulse Width Modulationfrequency, continuous or discontinuous conduction mode, and total outputpower. The operating values also provide the user with a currentanalysis, power dissipation analysis, and a description of severalvalues at the operating voltage and current of the circuit. The user canalso enter a different value for the operating voltage and operatingcurrent then recalculate the operating values based on these inputs.

SCHEMATIC DIAGRAM GENERATION

Referring to FIG. 13, an exemplary schematic diagram web page isillustrated that may be generated and delivered to a user in response touser selection of schematic button 1008, or by clicking link 1012, or byselecting button 1014 which goes to another page that allows access tothe to the electrical simulator. (See FIG. 10(A and B)). The schematicdiagram includes the components identified in the components list pagearranged in a circuit that satisfies the requirements specified by theuser. According to one embodiment, the schematic diagram generationmodule 416 used to generate the schematic web pages is the WebSIM moduleavailable from Transim, Inc. The specific features of the WebSIM moduleare beyond the scope of the present invention, and therefore shall notbe described in detail.

While the illustrated embodiment uses the WebSIM module for generatingschematic diagram web pages, the present invention is not limited to anyparticular schematic diagram generation module 416. Any module capableof generating a schematic diagram based on a list of components andschematic information may be used.

Thermal Simulation

The user may select a control from one of the previous exemplary webpages to create a thermal simulation. For example, the user may selectlink 1010 (FIG. 10A) or button 1014 (FIG. 10A), which takes the user toanother page that allows selection of the thermal simulator. The usermay elect to perform a thermal simulation at any time during the processafter the user has chosen the components for the circuit.

FIG. 14 illustrates a control panel window for helping to control theelectrical simulation of the circuit shown in FIG. 13. The user mayselect various analysis method, start frequency, stop frequency, and thelike. The user may also create bode plots of the analysis.

Referring to FIG. 15, an exemplary web page is displayed which listsinstructions to conduct the thermal simulation. The web page includes alist with links 1510 to any previous thermal simulations that have beenperformed for the current design. Link 1520 provides access to allthermal simulations conducted by the user for all designs. To start anew thermal simulation of the circuit the user selects the Start a newWEBTHERM simulation link 1530. Selecting link 1530 directs thermalsimulation module 422 to display a thermal simulation setup web page.

FIGS. 16A and 16B show an exemplary web screen illustrating setup ofthermal simulation of the circuit designed according to the user'srequirements. The thermal simulation helps the user to identify heatproblems on the printed circuit board early on in the design process andcorrect the issues before the board goes into production. This can savea lot of time and avoid costly quality accidents.

Briefly described, the thermal tool simulates the thermal behavior of anelectronic printed circuit board having components. The thermalsimulator uses validated thermal models for the components and thereference PCB. According to one embodiment of the invention, thermalsimulation module 422 used to conduct the thermal simulations isWebTHERM module provided by Flomerics, Inc. The user defines theenvironment, and the problem is solved using the thermal simulator'sconduction, radiation and convection solver. According to one embodimentof the invention, the output of the thermal simulation is a color plotof the PC board under the design's steady state electrical loadconditions. No special hardware is required to run the thermalsimulation. Instead, the user views the thermal simulation in the webbrowser. Designers may seamlessly qualify their designs from a thermaland electrical standpoint. Integration of these tasks over a network isa major improvement in design accuracy and can save a significant amountof time in the design cycle.

When the new simulation button (link 1530 as shown in FIG. 14) isselected, a screen appears with a drawing of the printed circuit boardlayout 1610 for the design, and areas that allow the user to specifyoptions for thermal simulation. A picture of the physical layout of thePC board appears in the user's web browser, showing the placement ofeach component and the copper routing. There are controls for adjustingcharacteristics for the thermal simulation, including controls for theboard orientation, edge temperature and airflow direction and speed,copper thickness, operating input voltage and operating output current,and board orientation, which allow the user to adjust parameters for thesimulation.

Printed circuit board display 1610 consists of copper interconnect lines1615 and top view drawings 1620 of the various components for the designwhich are placed in the appropriate positions on PCB 1625. Thesecomponents may include parts from many different sources. According toother embodiments, the board and components may be displayeddifferently. For example, a three-dimensional representation of theboard may be displayed to the user.

According to another embodiment of the invention, the user may specifyalternate locations for the components on the PCB or alternate copperinterconnect lines or routing of the lines. Additionally, the user mayclick on a select alternate components button for a given componentdirectly from the screen. The user may then select alternate componentsto replace the selected component or obtain additional information aboutthese components. The user could also manually enter the component'svalues in a custom component input box.

According to another embodiment, the user may move the components on thePCB. According to one embodiment, the user is limited to moving thecomponents within specified regions of the PCB to help ensure assurethat the electrical connections are maintained. This allows the user tomove the components farther apart or closer together which is animportant factor affecting the temperature of the board and components.

According to yet another embodiment, the user may change the locationand size of the copper areas on the board by clicking on a copper shape,which brings up controls to change the size and/or move the coppershape. Changing the copper area on the board affects the thermalcharacteristics of the design.

Referring to FIGS. 16A and 16B, temperature characteristics of thecircuit may be specified by the user. For example, the edge temperatureof the board may be specified as insulated or a specific temperature.These characteristics are specified in input boxes 1630, 1635, 1640, and1645 adjacent to the corresponding edges of PCB 1625. The input boxeshave a check box to specify insulated and another input box that allowsthe user to enter the edge temperature. According to one embodiment,when the user checks insulated, the edge temperature changes to N/A ordims out. If the user enters a specific temperature, the insulated checkbox is automatically unchecked.

Controls 1650 allow the user to specify the ambient temperature aroundthe top (component) side and bottom side of the board. Controls (notshown) may be provided to specify the ambient temperature at differentlocations of the board. Airflow controls 1655 allow the speed anddirection of the airflow to be specified. According to one embodiment,the direction of airflow is specified by clicking on a radio button inan array of radio buttons surrounding a picture of a board. The radiobutton clicked specifies which side of the board the airflow comes from.According to one embodiment, the airflow may be adjusted to come fromany point, or points, from around the board.

Simulation ID input box 1660 allows the user to enter a text name forthe simulation. The user may also enter comments about the simulation incomments input box 1665.

Control 1680 allows the user to change the copper weight of the board.

After entering the desired parameters for simulation, the user submitsthe simulation job to thermal simulation module 422 by selecting submitbutton 1670. A status screen then appears to allow the user to check thesimulation progress. A simulation typically takes two to three minutesto complete, excluding queue time. This time varies according to manydifferent factors, including: complexity of simulation, demand onserver, network conditions, and the like.

FIGS. 17-19 illustrate exemplary simulation status screens. After theuser submits the simulation, the simulation status screen appears. Thestatus of all the simulations is indicated in a table along with thetime at which that status began. The status is “queued” (See FIG. 17),“processing” (See FIG. 18) or “completed” (See FIG. 19). At any pointduring the simulation, the user may select refresh button 1710 to updatethe status of the simulation. When a simulation is completed, the usermay click on the appropriate simulation link in the table to view theresults. After the simulation is complete, the user can view the result,a full color plot of the temperature across the board (See FIG. 19 andrelated discussion). The temperature of each component is also listed inan accompanying table. If desired, the user can adjust parameters andresubmit the job for simulation.

FIGS. 20A and 20B show an exemplary result of a thermal simulation. Thesimulation results image 2010 shows outlines of the PCB copperinterconnect and components and is labeled with the names ofinterconnect traces and component names. Superimposed on top of the PCBcopper interconnect and components is a color plot of the temperaturesacross the board. The color of a specific region indicates thetemperature of that region. For example, variations of red may indicatehotter temperatures, while variations of blue may indicate coldertemperatures. Many coloring schemes may be chosen to indicatetemperature differences. All that is required is that the user be ableto differentiate between areas on the board that are above a user'sdesired operating temperatures. According to one embodiment of theinvention, the user may select the range of temperature to view. Forsome parts, the top surface temperature is plotted. For instance, thetemperature of the top surface for passive components and the board isplotted. The temperature of an internal part, such as the die, of eachcomponent may also be plotted, since this temperature is usually thehottest part of the component. This temperature may be represented by asquare or rectangle plotted within the component. The size of thissquare or rectangle does not have to be to scale if it is desired toconceal the die size or other internal part from the user. A scale 2020next to the plot indicates the temperatures corresponding to the colors.As will be appreciated by those of ordinary skill in the art in view ofthe present disclosure, other surfaces of the components may be plotted.For example, a three-dimensional plot of the PCB board and componentsmay be shown.

The names of each component and the numeric temperatures of eachcomponent are indicated in table 2030. The temperatures of the componentmay be the maximum temperature or other critical temperature such as thedie temperature. The user is given the option to rescale the maximum andminimum temperatures represented in the plot of the results. This isspecified in entry boxes 2040 that allow the user to enter the minimumand maximum temperatures. According to one embodiment, the user clickson a link to initiate the rescaling process. The resealing may alsoautomatically be done after entering a new value into entry boxes 2040.It will be appreciated by those of ordinary skill in the art, in lightof the present disclosure, that the same simulation parameter displaysare shown on this screen as were shown on the initial simulation launchscreen. This allows the user to review the parameter values that wereused in the simulation. The user may also change the parameter valuesand launch a new simulation from this screen. For example, suppose theuser determines that the IC should only reach a maximum temperature of130 degrees centigrade. Accordingly, the user may determine that a fanis required for the design. Suppose the user desires a fan having avelocity of 400 LFM coming from the edge closest to the IC. The userselects submit button 2050 which calls up a screen (FIGS. 16A and 16B)which allows the user to enter changes to run a new thermal simulationwith the changed parameters.

FIGS. 21A and 21B show an exemplary web page illustrating the results ofthe thermal simulation with the changed parameters. As can be seen byreferring to FIG. 21A, the temperature of the D1-diode has dropped from188° C. without a fan to 128° C. with the use of a fan. Once the user issatisfied with the thermal and electrical properties of the circuit, theuser may order the components or kit to construct the circuit.

Building The Circuit

According to one embodiment, one or more of the web pages provided tothe user include a control which, when selected, invokes componentacquisition module 424. The component acquisition module 424, in turn,provides one or more component acquisition web pages to the user. Thecomponent acquisition web pages include information and/or controls forordering the components from which the generated circuit is constructed.

In the embodiment illustrated in the figures, a “Build It” link button2060 (See FIG. 20A) is provided which, when selected, provides componentacquisition web pages to the user. The component acquisition web pagepresented to the user in response to selection of build it button 2110may, for example, contain the information shown in FIGS. 22A and 22B.

FIGS. 22A and 22B show an exemplary BUILD IT web page. The build it pageincludes a bill of materials section that identifies the list of theparts used in the circuit. A user can check to see if the parts are instock and get pricing information for the components. Graphicalrepresentations of the components are also included in the bill ofmaterials if they are available.

Selecting button 2220 on the BUILD IT page allows the user to view anassembly diagram document for the board that shows the locations of allthe components and gives assembly and soldering instructions. Thisdocument may also be e-mailed to the user or made downloadable to theuser in various formats.

FIGS. 23A-23F illustrate an exemplary assembly diagram documentaccording to one embodiment of the invention. The assembly diagramdocument includes an assembly diagram, bill of materials, an electricalschematic, topside and bottom side copper lay out diagrams, andinstructions for building and testing the power supply. The assemblydiagram also includes buttons allowing the user to download the boardlayout or schematic in Protel format, and the Gerber file for making theboard. The information contained within the assembly diagram isautomatically created by the system.

Referring again to FIG. 22A, the user may select documentation relatingto the circuit by selecting documentation button 2210.

FIG. 24 shows an exemplary documentation page provided to the user afterselecting documentation button 2210. From the Design Doc link the usermay obtain the previously described assembly document. Also, by clickinglink 2440, the full documentation of the design (Design Document)including the specifications, operating values and thermal simulationresults can be obtained. A detailed summary of the integrated circuitwith links to the datasheet and application notes is available byselecting the Product Folder button 2420 associated with the selectedIC. Downloadable schematics, layout and Gerber files are also available.This enables the user to easily integrate the design into the user'slocal CAD environment. According to one embodiment of the invention, theschematic and layout files are in Protel format. According to otherembodiments of the invention, other layout formats may be provided. TheGerber file is for the custom board used for this design.

FIGS. 25A-25E illustrate an exemplary design document, according to oneembodiment of the invention. The design document includes many sections,including: an introduction; design specifications; schematic; operatingvalues; information on the selected IC; a bill of materials; thermalsimulation results; BuildIt! Information; and appendices includingadditional information, such as the number of thermal simulationsperformed on the design.

Returning to FIGS. 22A and 22B, when the user is has completed reviewingthe bill of materials and other information, the user may click on theOrder this Kit button 2230 to order the kit. According to oneembodiment, the party that would handle the order of a single componentwould be the manufacturer or distributor of the component. However, theparty that handles the “kit” order may be a third party. In response tothe order of a kit, the party from whom the kit is ordered placescorresponding component orders with the component manufacturers orobtains the parts from a local stock in a warehouse. The process ofplacing the corresponding component order can be executed automaticallyupon receipt and approval of a kit order.

If the user selects Order this Kit button 2230, the user will have theability to receive the components and bare PC board to make the circuit.However, the user may prefer to receive the circuit itself, alreadyassembled. Therefore, the user may alternatively or additionally bepresented with an “order built-up board” button (not shown), which, whenselected, causes the components, and optionally a PC board, to beordered and sent to a circuit board assembler. The circuit boardassembler assembles the circuit board from the ordered components anddelivers the custom-assembled circuit board to the user that placed theorder.

Under some circumstances, circuit board manufacturers may already haveprefabricated circuit boards that are similar to the automaticallydesigned circuit, or they may have to generate one specifically for thedesign. According to one embodiment, the server-side database includesinformation about such prefabricated circuit boards, and presents themto the user when the similarity between the prefabricated boards and theusers requirements exceeds a predetermined similarity threshold. Theprefabricated boards may be presented, for example, on the suggestedcomponent web page, the bill of materials web page, and/or the componentacquisition web page, or the thermal simulation launch page where theamount of copper area for each board option is presented as a parameterto the user.

Persistent Storage Of Designs

A user may not be prepared to order the components of a circuit duringthe same session in which the circuit is generated for the user usingthe techniques described above. Therefore, according to one embodimentof the invention, a mechanism is provided for storing the designspersistently on a server-side storage device. The designs may be stored,for example, in a server-side database that associates the designs withthe user-id of the user that created the design. The event that triggersthe storage of a design in the database may be, for example, thecreation of the design or making a change in the design. Alternatively,a control may be provided which, when selected, causes the designs to besaved.

FIG. 26 shows an exemplary “my designs” page. The user may select the“My Designs” button included on one of the web pages. When a userselects my designs control, a saved designs web page that lists all ofthe saved designs for the user is presented to the user. The saveddesigned web page illustrated in FIG. 26 includes listings of a user'spreviously saved designs. The listing includes, for each saved design, adesign ID, a design name, the model number of the integrated circuitaround which the design is built, the creation date of the design,modification dates to the design, the name of the “design assistant”tool used to create the design, comments, and a design operation field.

Controls are provided to allow the user to modify, analyze, build, addnotes, delete, and share the design with a colleague. Selection of thecontrols may result in the delivery of an appropriate web page, asdescribed above. Selection of the delete, change name or add commentscontrols causes corresponding information to be deleted, changed, oradded to the server-side database.

The user may share a design with another user. For example, a first usermay select one or more of the first user's designs, and then specify oneor more second users with whom the design is to be shared. In response,the server-side database is updated to include a copy of the design forthe one or more second users. Also, an e-mail is sent to the seconduser(s) notifying them of the event. When one of the second users ispresented with a list of available saved designs, any designs that havebeen shared with the user are included in the list.

To share the design, the first user enters the e-mail of the seconduser(s). If the second user(s) in not currently registered for WEBENCH,a user ID and password are created for the new user and an e-mail issent to the new user to notify the second user(s) of the event.

System Overview

FIGS. 1-3 illustrate an exemplary environment for practicing theinvention. Aspects of the present invention are embodied in a World WideWeb (WWW) site accessible via the Internet according to one embodimentof the invention. Generally, the term “Internet” refers to the worldwidecollection of networks and gateways that use the Transmission ControlProtocol/Internet Protocol (“TCP/IP”) suite of protocols to communicatewith one another. At the heart of the Internet is a backbone ofhigh-speed data communication lines between major nodes or hostcomputers, including thousands of commercial, government, educational,and other computer systems, that route data and messages. Arepresentative section of the Internet 100 is shown in FIG. 1.

FIG. 1 shows a plurality of local area networks (“LANs”) 120 _(a-d) andwide area network (“WAN”) 130 interconnected by routers 110. Routers 110are intermediary devices on a communications network that expeditemessage delivery. On a single network linking many computers through amesh of possible connections, a router receives transmitted messages andforwards them to their correct destinations over available routes. On aninterconnected set of LANs—including those based on differingarchitectures and protocols—, a router acts as a link between LANs,enabling messages to be sent from one to another. Communication linkswithin LANs typically include twisted wire pair or coaxial cable, whilecommunication links between networks may utilize analog telephone lines,full or fractional dedicated digital lines including T1, T2, T3, and T4,Integrated Services Digital Networks (ISDNs), Digital Subscriber Lines(DSLs), wireless links including satellite links, or othercommunications links known to those skilled in the art. Furthermore,computers, such as remote computer 140, and other related electronicdevices can be remotely connected to either LANs 120 or WAN 130 via amodem and temporary telephone link. A remote computer may act in anumber of ways, including as a WWW server as described in FIG. 2 or aclient computer as described in FIG. 3. It will be appreciated that theInternet 100 comprises a vast number of such interconnected networks,computers, and routers and that only a small, representative section ofthe Internet 100 is shown in FIG. 1.

The media used to transmit information in communication links asdescribed above illustrates one type of computer-readable media, namelycommunication media. Generally, computer-readable media includes anymedia that can be accessed by a computing device. Computer-readablemedia may include computer storage media, communication media, or anycombination thereof.

Communication media typically embodies computer-readable instructions,data structures, program modules, or other data in a modulated datasignal such as a carrier wave or other transport mechanism and includesany information delivery media. The term “modulated data signal” means asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in the signal. By way of example,communication media includes wired media such as twisted pair, coaxialcable, fiber optics, wave guides, and other wired media and wirelessmedia such as acoustic, RF, infrared, and other wireless media. TheInternet 100 may include networks constructed from, coupled to, orconnected with any type or combination of communication media.

The Internet has recently seen explosive growth by virtue of its abilityto link computers located throughout the world. As the Internet hasgrown, so has the WWW. Generally, the WWW is the total set ofinterlinked hypertext documents residing on HTTP servers around theworld. Documents on the WWW, called pages or Web pages, are typicallywritten in HTML (Hypertext Markup Language) or some other markuplanguage, identified by URLs (Uniform Resource Locators) that specifythe particular machine and pathname by which a file can be accessed, andtransmitted from server to end user using HTTP (Hypertext TransferProtocol). Codes, called tags, embedded in an HTML document associateparticular words and images in the document with URLs so that a user canaccess another file, which may literally be halfway around the world, atthe press of a key or the click of a mouse. These files may contain text(in a variety of fonts and styles), graphics images, movie files, mediaclips, and sounds as well as Java applets, ActiveX controls, or otherembedded software programs that execute when the user activates them. Auser visiting a Web page also may be able to download files from an FTPsite and send messages to other users via e-mail by using links on theWeb page.

A WWW server is a computer connected to the Internet having storagefacilities for storing hypertext documents for a WWW site and runningadministrative software for handling requests for the stored hypertextdocuments. A hypertext document normally includes a number ofhyperlinks, i.e., highlighted portions of text which link the documentto another hypertext document possibly stored at a WWW site elsewhere onthe Internet. Each hyperlink is associated with a URL that provides thelocation of the linked document on a server connected to the Internetand describes the document. Thus, whenever a hypertext document isretrieved from any WWW server, the document is considered to beretrieved from the WWW. As is known to those skilled in the art, a WWWserver may also include facilities for storing and transmittingapplication programs, such as application programs written in the JAVAprogramming language from Sun Microsystems, for execution on a remotecomputer. Likewise, a WWW server may also include facilities forexecuting scripts and other application programs on the WWW serveritself.

A user may retrieve hypertext documents from the WWW via a WWW browserapplication program. A WWW browser, such as Netscape's NAVIGATOR® orMicrosoft's INTERNET EXPLORER®, is a software application program forproviding a graphical user interface to the WWW. Upon request from theuser via the WWW browser, the WWW browser accesses and retrieves thedesired hypertext document from the appropriate WWW server using the URLfor the document and HTTP. HTTP is a higher-level protocol than TCP/IPand is designed specifically for the requirements of the WWW. HTTP isused to carry requests from a browser to a Web server and to transportpages from Web servers back to the requesting browser or client. The WWWbrowser may also retrieve application programs from the WWW server, suchas JAVA applets, for execution on a client computer.

FIG. 2 shows an exemplary WWW server 200 that is operative to provide aWWW site. Accordingly, WWW server 200 transmits WWW pages to the WWWbrowser application program executing on client computer 300 (FIG. 3) tocarry out this process. For instance, WWW server 200 may transmit pagesand forms for receiving information about a user, such as address,telephone number, billing information, credit card number, etc.Moreover, WWW server 200 may transmit WWW pages to client computer 300that allow a consumer to participate in a WWW site. The transactions maytake place over the Internet 100 or some other communications networkknown to those skilled in the art.

Those of ordinary skill in the art will appreciate that the WWW server200 may include many more components than those shown in FIG. 2.However, the components shown are sufficient to disclose an illustrativeembodiment for practicing the present invention. As shown in FIG. 2, WWWserver 200 is connected to Internet 100, or other communicationsnetwork, via network interface unit 210. Those of ordinary skill in theart will appreciate that network interface unit 210 includes thenecessary circuitry for connecting WWW server 200 to Internet 100, andis constructed for use with various communication protocols includingthe TCP/IP protocol. Typically, network interface unit 210 is a cardcontained within WWW server 200.

WWW server 200 also includes processing unit 212, video display adapter214, and a mass memory, all connected via bus 222. The mass memorygenerally includes RAM 216, ROM 232, and one or more permanent massstorage devices, such as hard disk drive 228, tape drive, optical drive226, and/or floppy disk drive. The mass memory stores operating system220 for controlling the operation of WWW server 200. It will beappreciated that this component may comprise a general purpose serveroperating system as is known to those of ordinary skill in the art, suchas UNIX, LINUX™, or Microsoft WINDOWS NT®. Basic input/output system(“BIOS”) 232 is also provided for controlling the low-level operation ofWWW server 200.

The mass memory as described above illustrates another type ofcomputer-readable media, namely computer storage media. Computer storagemedia may include volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage ofinformation, such as computer readable instructions, data structures,program modules or other data. Examples of computer storage mediainclude RAM, ROM, EEPROM, flash memory or other memory technology,CD-ROM, digital versatile disks (DVD) or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to store thedesired information and which can be accessed by a computing device.

The mass memory also stores program code and data for providing a WWWsite. More specifically, the mass memory stores applications includingWWW server application program 230. WWW server application program 230includes computer executable instructions which, when executed by WWWserver computer 200, generate WWW browser displays, including performingthe logic described above. WWW server 200 also has functional modules234, which perform logical operations as described below. WWW serverapplication program 230 may also create and transmit displays describedin conjunction with FIGS. 4-15. WWW server 200 may also include a JAVAvirtual machine, an SMTP handler application for transmitting andreceiving e-mail, an HTTP handler application for receiving and handingHTTP requests, JAVA applets for transmission to a WWW browser executingon a client computer, and an HTTPS handler application for handlingsecure connections. The HTTPS handler application may initiatecommunication with an external security application or a credit cardprocessing application for communicating with remote financialinstitutions in a secure fashion.

WWW server 200 also comprises input/output interface 224 forcommunicating with external devices, such as a mouse, keyboard, scanner,or other input devices not shown in FIG. 2. Likewise, WWW server 200 mayfurther comprise additional mass storage facilities such asCD-ROM/DVD-ROM drive 226 and hard disk drive 228. Hard disk drive 228 isutilized by WWW server 200 to store, among other things, applicationprograms, databases, and program data used by WWW server application230. For example, customer databases, product databases, imagedatabases, and relational databases may be stored. The operation andimplementation of these databases is well known to those skilled in theart.

FIG. 3 depicts several components of client computer 300. Those ofordinary skill in the art will appreciate that client computer 300 mayinclude many more components than those shown in FIG. 3. However, it isnot necessary that those generally conventional components be shown inorder to disclose an illustrative embodiment for practicing the presentinvention. As shown in FIG. 3, client computer 300 includes networkinterface unit 302 for connecting to a LAN or WAN, or for connectingremotely to a LAN or WAN. Those of ordinary skill in the art willappreciate that network interface unit 302 includes the necessarycircuitry for such a connection, and is also constructed for use withvarious communication protocols including the TCP/IP protocol, theparticular network configuration of the LAN or WAN it is connecting to,and a particular type of coupling medium. Network interface unit 302 mayalso be capable of connecting to the Internet through a point-to-pointprotocol (“PPP”) connection or a serial line Internet protocol (“SLIP”)connection as known to those skilled in the art.

Client computer 300 also includes BIOS 326, central processing unit 306,video display adapter 308, and memory. The memory generally includesrandom access memory (“RAM”) 310, read-only memory (“ROM”) 304 and apermanent mass storage device, such as a disk drive. The memory storesoperating system 312 and programs 334 for controlling the operation ofclient computer 300. Programs 334 may include programs described inconjunction with circuit design and ordering. The memory also includesWWW browser 314, such as Netscape's NAVIGATOR® or Microsoft's INTERNETEXPLORER® browsers, for accessing the WWW. It will be appreciated thatthese components may be stored on a computer-readable medium and loadedinto memory of client computer 300 using a drive mechanism associatedwith the computer-readable medium, such as a floppy drive (not shown),optical drive 316 or some other optical drive, or hard drive 318.Input/output interface 320 may also be provided for receiving input froma mouse, keyboard, or other input device. The memory, network interfaceunit 302, video display adapter 308, and input/output interface 320 areall connected to central processing unit 306 via bus 322. Otherperipherals may also be connected to central processing unit 306 in asimilar manner.

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

We claim:
 1. A method for creating a PC board (PCB) layout for acircuit, the PCB having predetermined landing areas, comprising:determining components of the circuit; determining the predeterminedlanding areas in which to place the components; and placing thecomponents on the determined landing areas.
 2. The method of claim 1,further comprising cropping the PCB to a size.
 3. The method of claim 2,wherein the cropping the PCB to the size further comprises: determiningthe size to crop the PCB; and cropping the PCB to the determined size.4. The method of claim 3, wherein determining the size to crop the PCBis determined by obtaining a width crop area to crop the width of thePCB and obtaining a height crop area to crop the height of the PCB. 5.The method of claim 4, wherein obtaining the width crop area andobtaining the height crop area further comprises, obtaining from a userthe width crop area and the height crop area.
 6. The method of claim 4,wherein obtaining the width crop area and obtaining the height crop areafurther comprises, automatically determining the width crop area and theheight crop area.
 7. The method of claim 4, wherein the landing areas onthe PCB, further comprise: an inductor area arranged to accommodate aninductor; an output capacitor area arranged to accommodate an outputcapacitor; a diode area arranged to accommodate a diode; an IC areaarranged to accommodate an IC; a small signal component area arranged toaccommodate a small signal component; and an input capacitor areaarranged to accommodate an input capacitor.
 8. The method of claim 7,wherein the landing areas are designed for a power circuit.
 9. Themethod of claim 1, wherein determining the components of the circuit,further comprises: simulating the circuit over a network; producing aresult based on the simulation of the circuit; and determining thecomponents based on the simulation of the circuit.
 10. The method ofclaim 9, wherein determining the landing areas in which to place thecomponents, further comprises determining, in response to the result,the landing areas configured to accept the components.
 11. The method ofclaim 10, further comprising: allowing a characteristic of the circuitto be changed; determining when the characteristic of the circuit hasbeen changed; and performing another simulation of the circuit when adetermination has been made that the characteristic of the circuit hasbeen changed.
 12. A PC board (PCB) having predefined landing areas forcomponents of a circuit, comprising: an inductor landing area arrangedto accommodate an inductor; an output capacitor landing area arranged toaccommodate an output capacitor; a diode landing area arranged toaccommodate a diode; an IC landing area arranged to accommodate an IC; asmall signal component landing area arranged to accommodate a smallsignal component; and an input capacitor landing area arranged toaccommodate an input capacitor.
 13. The PCB of claim 12, wherein the PCBis arranged to be cropped to a size.
 14. The PCB of claim 13, whereinthe PCB that is arranged to be cropped to the size further comprises,cropping the PCB to the size in response to a user's specifications. 15.The PCB of claim 14, wherein cropping the PCB to the size in response tothe user's specifications is determined automatically.
 16. The PCB ofclaim 14, wherein cropping the PCB to the size in response to the user'sspecifications is determined in response to the user moving a control toindicate the size to be cropped from the PCB.
 17. An apparatus forcreating a PC board (PCB) layout for a circuit, the PCB havingpredetermined landing areas, comprising: a means for determiningcomponents of the circuit; a means for determining the predeterminedlanding areas in which to place the components; and a means for placingthe components on the determined landing areas.
 18. The apparatus ofclaim 17, further comprising a means for cropping the PCB to a sizebased on specifications of the circuit.